Large populations of birds raised in enclosed environments for commercial purposes under crowded conditions are highly susceptible to the spread of infectious agents.
Consequently, poultry typically are vaccinated to afford protection against a number of diseases, particularly of viral origin, that could otherwise decimate a flock. Optimum protection is most often afforded by vaccinating young birds or chicks.
While vaccines can be dispensed to individual birds or chicks by injection delivery, such a procedure is expensive, time-consuming and labor-intensive. Manual handling of the chicks can induce stress or injury from the needle, and may even initiate secondary infections from cross-contamination. Automatic inoculation devices that rapidly inject birds reduce the disadvantages of manual injection, but cannot eliminate individual handling each bird or chick.
Such devices offer automatic charging of syringes and introduction of the injection needle into a bird held against the device, which then delivers the inoculum dose. Alternative methods to injection delivery that are less injurious to the birds have included the manual dispensation of liquid vaccines directly to the mouths, eyes or respiratory channels of chicks. However, these methods remain labor-intensive and costly.
Spray delivery of aerosolized vaccines allows the simultaneous treatment of large numbers of chicks without the disadvantage of manual handling of individual birds. The vaccine fluid is delivered to a flock of chicks by direct contact of the vaccine droplets with the eye, or the spray mist is inhaled to contact the respiratory tract. Spray delivery apparatus pass containers with chicks beneath a fixed spray nozzle using a conveyor belt or maximize spray coverage of the chicks by using multiple overhead spray nozzles, such as described in U.S. Pat. No. 4,316,464 to Peterson. Conveyor belt systems, however, are complex and costly and not readily transportable, requiring that the chick containers be brought to the site of vaccination.
Fixed spray jets are usually ejected from spray nozzles with a circular configuration that results in areas of a rectangular container receiving inadequate exposure to fluid, or spraying beyond the container resulting in significant wastage of expensive vaccine fluid. Spray jets may also be oval and provide a fan-shaped spray that may more completely cover the area of the chick container.
What is needed, therefore, is a spray delivery system that provides a uniform spraying of a container, with minimal vaccine wastage, but resulting in maximum exposure of the recipient chicks to the vaccine. What is further needed is a spray delivery system capable of delivering a fluid spray to a container of birds but does not require complex and costly container conveyor belt systems to pass the birds under the fluid spray.